The present invention relates to a folding ladder and, more particularly, to a ladder that is laterally foldable.
Conventional straight ladders and step ladders have left and right side rails and one or more, usually a plurality, of rungs rigidly attached between the side rails. Such conventional ladders occupy a substantial amount of space due to the large open spaces between the rungs and the rails.
Step ladders typically include legs that are pivotally attached to top ends of the side rails so that, when the step ladder is not in use, the legs can be folded to a position in which they are substantially adjacent to and parallel with the side rails. However, the step ladder still occupies a substantial amount of space due to the large open spaces between the rungs and the rails.
Various attempts have been made to provide a ladder that can be laterally folded so that the rungs are substantially parallel to the legs and, when the ladder is not in use, it does not occupy as much space as when in use. U.S. Pat. No. 4,463,829, for example, discloses a foldable ladder having an arrangement of parallel rails with pivotally connected rungs. A ladder of this type can be folded to a dimension that is a fraction of that of the ladder in the unfolded condition.
One drawback to the use of foldable ladders is that they tend to be lacking in stability. It is, therefore, desirable to provide a foldable ladder that is highly stable when in an open condition.
According to one aspect of the present invention, a folding ladder includes a first side rail and a second side rail, and at least one rung having a first end portion and a second end portion, the first end portion being pivotally attached to the first side rail and the second end portion being pivotally attached to the second side rail, the rung being pivotable relative to the first side rail and the second side rail between a use position in which the rung is substantially perpendicular to each of the first side rail and the second side rail and a closed position in which the rung is substantially parallel to each of the first side rail and the second side rail. The ladder further includes at least one diagonal locking member having a first portion pivotally attached at a first end to the first side rail and a second portion pivotally attached at a first end to a second end of the first portion and a second end pivotally attached to the second side rail, the first portion and the second portion being in a substantially parallel closed position when the rung is in the closed position and being pivotable relative to each other to a locking position in which the first portion and the second portion are substantially parallel to each other and non-perpendicular to the first side rail and the second side rail when the rung is in the use position, the locking member including a stop disposed on at least one of the first portion and the second portion for preventing the first portion and the second portion from pivoting relative to each other beyond the locking position.